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What are VRLA Batteries?

Batteries Plus Blog - Power - by Bryan Veldboom - updated on 5/4/2022

X2Power Dual Purpose AGM battery

At some point, you might have heard the term VRLA used to describe the battery used in a wheelchair, UPS backup, car or other vehicle and wondered what that meant. VRLA is short for Valve Regulated Lead Acid, a special type of lead acid battery that was first developed in the mid 1960s. Today we'll be discussing VRLA batteries, including how they work, what types are available and what they are typically used for.

What is the Difference Between a VRLA and a Lead Acid Battery?

The key difference between VRLAs and traditional flooded lead acid batteries is that they're completely sealed, which is why they're alternatively known as Sealed Lead Acid (SLA) batteries. Since they are sealed, VRLA batteries are essentially spill-proof, which allows them to be mounted in a variety of positions that aren't possible with flooded batteries.

Another difference lies in how the batteries' electrolytes are maintained. When a flooded battery is charged, it loses water due to the evaporation of gasses. This requires you to replace the lost water by topping off the electrolyte inside with distilled or deionized water. VRLA batteries, however, are equipped with a one-way pressure relief valve that prevents gas from escaping. When the battery charges, the gasses recombine into water via a process called oxygen recombination. This makes a VRLA battery completely maintenance free.

What are the Advantages of VRLA Batteries?

In addition to the advantages discussed above, VRLA batteries offer a number of additional benefits over flooded options.

  • Higher voltage output - VRLAs provide more electrical energy than flooded batteries
  • Faster recharge rates - VRLAs can recharge up to 5X faster than flooded batteries
  • Longer lifespans - VRLAs can last 2-3X as long as flooded batteries
  • Slower discharge rates - VRLAs lose their charge much slower in storage
  • Minimal gassing - VRLAs can be used without need for special ventilation
  • Temperature resistant - VRLAs do a better job of standing up to extreme heat and cold
  • Vibration resistant - VRLAs are more resistant to vibration, making them great for boats & watercraft

What are the Different Types of VRLA Batteries?

There are two types of VRLA batteries: AGM and gel. The big difference between the two lies in how their electrolyte is stored. In a flooded battery, the electrolyte is a free-flowing liquid. In an AGM (short for Absorbed Glass Mat) battery, the electrolyte is absorbed in a series of fiberglass separators, set between the battery's plates and held there in suspension. In a gel battery, the sulfuric acid in the electrolyte is mixed with a silica additive, which transforms the electrolyte into a thick gel-like substance.

What are VRLA Batteries Used For?

AGM batteries perform best in high current, high power applications, such as starting batteries for cars and other vehicles. They're also quite popular with boat and RV owners, since an AGM battery can serve as a dual purpose battery, providing the strong starting power needed to start an engine, as well as the cycling capacity to run additional accessories.

Gel batteries can discharge much deeper than AGM batteries can. This makes them ideal for cycling operations that require heavy, everyday use. Some common uses for gel batteries include: marine trolling motors, wheelchairs & mobility scooters, marine & RV house power, UPS and other backup applications. One thing to keep in mind is that gel batteries don't perform well in cold temperatures since their power declines much faster than an AGM once the temperature drops below 32℉.

Find the Right VRLA Battery for Any Application

Batteries Plus has an enormous selection of AGM and gel batteries for your home, vehicle and commercial needs. Visit our Battery Page to find the best batteries for cars, boats, UPS backups and more. You can also pick up a spare battery charger online or at your nearest Batteries Plus location. VRLA batteries require a lower charging voltage than flooded batteries, so be sure that the battery charger you select has a setting specifically for AGM or gel batteries.

Want to learn more about VRLA batteries? We have plenty of informative articles in our online blog. Some related topics include "Which Type of SLA Batteries Does Your Business Need?" and "Do SLA Batteries Need Venting?"

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